Some notes from when I tweaked one of these units

This is based on the AC8227L JCAC10003 version, I originally ordered from here: https://www.aliexpress.com/item/1005005259929995.html

Service/Factory Passwords: Factory Reset (1234), Developer Settings (5678), Other Settings (56789)

To Edit the following, you need to do a backup to USB, extract the iviconfig.zip using password jancar, afterwards you can rezip without password and import back into the headunit

To fix jumping volume around level 7:

Open ivi-config.ini, find the line:
BD37534VolumeCurve=-79.0(0)
Change to:
BD37534VolumeCurve=65.0(0),64.0(1),61.0(2),59.0(3),57.0(4),55.0(5),53.0(6),51.0(7), 49.0(8),47.0(9),45.0(10),43.0(11),41.0(12),39.0(13),37.0(14),35.0(15),33.0(16),31.0(17),29.0(18),27.0(19),25.0(20),23.0(21),21.0(22),19.0(23),17.0(24),15.0(25),13.0(26), 11.0(27), 9.0(28),7.0(29),5.0(30),3.0(31),1.0(32),-1.0(33),-3.0(34),-5.0(35),-7.0(36), -9.0(37),-11.0(38),-13.0(39),-15.0(40)

I also changed the PreVolume values under [Audio] to all be '5', this helped balance volume levels between carplay/radio etc - It seemed to help differences in Siri volume but still need to tweak to get it perfect

If MIC Volume is too low:

Try the following,
Microphone Sensitivity Setting: Settings/Factory Settings/Password 56789/Enter Vehicle Settings/Other/Engineer Mode/ Hardware Testing/Audio
Internal Microphone, we need Normal Mode.
If an external microphone, we need Headset Mode.
In Type, select Mic (microphone), then, starting from Level0, increase the Value is indicator, as in the example, and save by pressing Set...
Naturally, without the meanings that, for example, in parentheses ...

____________________________________________________________________Example_________________________________________________________
(brackets is original value)
Level 0 - 220 press Set - (64)
Level 1 - 220 press Set (112)
Level 2 - 220 press Set (192)
Level 3 - 220 press Set (144)
Level 4 - 220 press Set (192)
Level 5 - 220 press Set (192)
Level 6 - 220 press Set (184) 
Level 7 - 220 press Set (184)
Level 8 - 220 press Set (184) 
Level 9 - 220 press Set (184) 
Level 10 - 220 press Set (184) 
Level 11 - 0 press Set (0) 
Level 12 - 0 press Set (0) 
Level 13 - 0 press Set (0) 
Level 14 - 0 press Set (0)
###############################################

To enable Carplay/AA:

In the file ivi-customer.ini

Change InterconnectAPP to '4'

Note: In this file, the seller can also specify fake CustomRAM/CustomROM values so be wary when purchasing as Memory may be fake

There is new firmware and alot of info on the russian 4pda forum but needs a google translate